Acetylene derivs cyclic

Homologization-rearrangement of N-heterocyclic side chains Allenes from acetylene derivatives Cyclic tert. amines from cyclimmonium salts by selective hydrogenation... 

The palladium catalysed annulation of / -iodoamines and acetylene derivatives has been widely used in the construction of pyrroles and indole derivatives. The strategy, first reported by Larock, is efficient in converting both cyclic and open chain 2-iodo-allylamine derivatives to 3-alkylidene-... 

Scheme IV/8. (n+2) Conversion of cyclic compounds by acetylene derivatives.

The arylacetylene phenylheptatriyne (Phe—C=C—C=C—C=C—CH 3) from Bidens, Dahlia and Coreopsis species (Asteraceae) has phototoxic antimicrobial activity as have 5-(3-buten-l-ynyl)-2,2 -bithienyl (thiophene—thiophene—C=C—C=CH2) and the cyclic disulfide acetylenes thiarubrine A (C3—(C4,S—S)—C6) and thiarubrine B (Cj-(C4,S-S)-C3). The photoactivation of acetylenes derives from light absorption by these conjugated systems and ready reaction with oxygen to form reactive intermediates. 

Sequential treatment of an ethynylalkanol acetate with butyllithium and a trialkyl-borane produces an allenic borane (23), which when protonated with acetic acid forms an allene, while upon treatment with water affords an acetylene derivative, presumably via a cyclic process (Eq. 51) A novel synthesis of homopropargylic... 

Sanders and coworkers have developed syntheses of rather rigid cyclic oligoporphyrins (porphyrin-linker), (n = 2 4) by catalytic-coupling reactions of acetylene derivatives with copper salts. In particular, incorporation of metal ions into cyclic porphyrin oligomers provides the multi-interaction sites necessary to tightly bind heterocyclic compounds in the inner cavity (see section IV).Rigidity of host molecules is controlled by the structure of the linkage moieties. 

Acetylene derivs. from osazones Cyclic acetylene derivs. 

Cyclic compds. 3 equivalents K-r rf-butoxide-dimethyl sulfoxide added at 20 to a stirred soln. of 2-bromo-3-methoxy- ran -cyclooctene in dimethyl sulfoxide, and the reaction quendied within 5 sec. by addition of cold aq. acetic acid 3-methoxycyclooctyne. Y 74%. F. e. s. C.B. Reese and A. Shaw, Chem. Commun. 1970, 1172 1972, 787 prepn. of cyclic acetylene derivs., review, s. H. Meier, Synthesis 1972, 235. 

Siliquariaspongia°, Theonella Macrolactones, atypical sterols, linear and cyclic peptides, cyclic depsipeptides, nitrogen-containing sesquiterpenes, pyridine derivatives, acetylenic derivatives, phosphorus derivatives analogues of calyculin, tetramic acid glycosides... 

Callyspongiidae 70-80 110-120 Callyspongia, Siphonochalina Acetylenic derivatives, macrolides, macroheterocycles, triterpenes, sulfated meroterpenes, azetidine and pyridine derivatives, cyclic peptides... 

Chalinidae 300-320 300-320 Adocia, Chalinula, Haliclona, Reniera Acetylenic derivatives, macro-heterocycles, triterpenes, sulfated meroterpenes, isonitriles, aromatic carotenoids, atypical sterols, long-chain phenols, pyridine derivatives, S/N heterocycles, cyclic peptides, sulfated derivatives... 

Mycalidae Mycale Cyclic peroxides, macrolides, diterpenes (isocopalane), brominated acetogenines en Cns, acetylenic derivatives, pyrrole derivatives... 

Methyl ketones are important intermediates for the synthesis of methyl alkyl carbinols, annulation reagents, and cyclic compounds. A common synthetic method for the preparation of methyl ketones is the alkylation of acetone derivatives, but the method suffers limitations such as low yields and lack of regioselectivity. Preparation of methyl ketones from olefins and acetylenes using mercury compounds is a better method. For example, hydration of terminal acetylenes using HgSO gives methyl ketones cleanly. Oxymercuration of 1-olefins and subsequent oxidation with chromic oxide is... 

A two-carbon ring expansion of cyclic ketones was achieved by the addition of acetylenic esters and diesters to the enamine derivatives of the ketones, and reported almost simultaneously from several laboratories (337-343). The intermediate bicyclic adduct could be isolated in some cases. 

A derivative of cyclopentyne has been trapped in a matrix. Although cycloheptyne and cyclohexyne have not been isolated at room temperatures, Pt(0) complexes of these compounds have been prepared and are stable." The smallest cyclic allene" so far isolated is l-/err-butyl-l,2-cyclooctadiene 107." The parent 1,2-cyclooctadiene has not been isolated. It has been shown to exist transiently, but rapidly dimerizes." " The presence of the rert-butyl group apparently prevents this. The transient existence of 1,2-cycloheptadiene has also been shown," and both 1,2-cyclooctadiene and 1,2-cycloheptadiene have been isolated in platinum complexes." 1,2-Cyclohexadiene has been trapped at low temperatures, and its structure has been proved by spectral smdies." Cyclic allenes in general are less strained than their acetylenic isomers." The cyclic cumulene 1,2,3-cyclononatriene has also been synthesized and is reasonably stable in solution at room temperature in the absence of air." ... 

Similar reactions have been carried out on acetylene. Aldehydes add to alkynes in the presence of a rhodium catalyst to give conjugated ketones. In a cyclic version of the addition of aldehydes, 4-pentenal was converted to cyclopen-tanone with a rhodium-complex catalyst. In the presence of a palladium catalyst, a tosylamide group added to an alkene unit to generate A-tosylpyrrolidine derivatives. ... 

Cyclic a,p-unsaturated ketones can be cleaved by treatment with base of their epoxy tosylhydrazone derivatives to give acetylenic ketones. The reaction can be applied to the formation of acetylenic aldehydes (R=H) by using the corresponding, 2,4-dinitrotosylhydrazone derivatives.Hydrazones (e.g., 47) prepared from... 

We can narrow the difference from 10 kJmol-1 even further once it is remembered that in the comparison of meso-bisallene, 27, and (Z, Z)-diene, 29, there are two extra alkylallene and alkylolefin interactions for which a stabilization of ca 3 kJ mol-1 for the latter was already suggested. Admittedly, comparison with the corresponding 1,5-cyclooctadiyne suggests strain-derived anomalies. From the enthalpy of hydrogenation, and thus derived enthalpy of formation, of this diyne from W. R. Roth, H. Hopf and C. Horn, Chem. Ber., 127, 1781 (1994), we find 1/2S (bis-allene, bis-acetylene) equals ca — 80 kJ mol-1. We deduce that the discrepancy of this last 5 quantity from the others is due to strain in the cyclic diyne. 

As an alternative to hydrozirconation of acetylenic tellurides or selenides, Dabdoub and co-workers have more recently described the first additions of the Schwartz reagent (one equivalent) to acetylenic selenide salts 51 (Scheme 4.30) [52]. Subsequent alkylation at selenium produces 1,1-dimetallo intermediates 52, which are cleanly converted in a one-pot process to stereodefined products 53. It is noteworthy that ketene derivatives 52 are of ( )-geometry, the opposite regiochemistry to that which results from hydrozirconation of acetylenic tellurides (vide supra). This new route also avoids the mixtures of regio-isomers observed when seleno ethers are used as educts. The explanation for the stoichiometric use of Cp2Zr(H)Cl in these reactions, in contrast to the requirement for two equivalents with seleno ethers, may be based on cyclic intermediates 54, in which Li—Cl coordination provides an additional driving force. Curiously, attempted hydrozirconation of the corresponding telluride salt 55 under similar conditions was unsuccessful (Scheme 4.31) (Procedure 12, p. 143). 

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